Player forgets it's a 1 and 1

[MajorCord]

Had this situation Saturday. Late in the game, player shooting 1 and 1. I'm administering free throws. I step in and clearly indicate it is 1 and 1. Partner at the trail does the same. Player shoots the first free throw, misses and the rebound comes back to him. Nobody moves, every player forgot it was 1 and 1. Player throws the ball (now live) towards me. I step out of the way and let it go out of bounds. Blow whistle for violation and give ball to other team. I know I did the right thing. Here is my question: how would you have handled it if I had caught the ball? Go to possession arrow?